Although all three hachines have completely different libc-versions
(between 2.7-5ubuntu2 and 2.7-9ubuntu2) it is sufficient to copy the
/usr/lib/openmpi/lib from the machine with openmpi1-1.2.5-1
to the two other machines. Rebuilding 1.2.5-1ubuntu1 on the
newer machines doesn't help.

Since the only changes in ubuntu-1 are fixed dangling pointers
and a maintainer field, I suspect it has to do with the build process.